The Chestnut-sided Warbler is a small, brightly colored songbird with distinctive field marks. Adults measure around 4.5 inches in length and weigh approximately 0.3 ounces. They have a yellow cap and white belly, with chestnut-colored sides that give them their name. They also have a black line through their eye and a white wing patch, making them easy to identify.

These birds breed in deciduous forests in the eastern United States and southern Canada. During the breeding season, males are highly territorial and can be heard singing their loud, sweet songs to attract mates. After breeding, they begin their migration to their wintering grounds in Central and South America.

During migration, Chestnut-sided Warblers can be seen in a variety of habitats, including forests, fields, and even suburban gardens. They are known for their energetic behavior as they flit from branch to branch, often flashing their distinctive plumage. Their migration begins in late summer and lasts until early fall.

In their wintering grounds, Chestnut-sided Warblers can be found in a variety of habitats, including scrublands, secondary growth forests, and coffee plantations. They are known to form mixed-species flocks with other small birds, which helps them forage more efficiently and avoid predators.

Despite their brightly colored plumage, Chestnut-sided Warblers can be challenging to spot as they move quickly and often stay high in the canopy. However, their distinct field marks and beautiful songs make them a favorite of birdwatchers and nature enthusiasts alike.